Low-velocity, launcher-fired 40 mm grenades or rounds are known in the art. Standard issue 40 mm grenades, such as the M-433 with its shaped charge and fragmenting body or case, are designed to defeat light armor and personnel. The M-433 grenade is designed for maximum fragmentation and is therefore unacceptable for breaching doors and other barricades due to the high probability of collateral damage and gunner injury. A detailed discussion of the propulsion system of the M-433 and a typical fuzeH assembly, the M-550 point-initiating, base-detonating fuze, is beyond the scope of this disclosure. The reader is referred to U.S. Pat. No. 5,081,929 to Mertens (1992), which is hereby expressly incorporated by reference.
With war fighting moving to urban environments, these 40 mm grenades are being fired at shorter distances and are being used to breach doors and other barricades, but with little effectiveness due to the small amount of explosive in the ammunition. These rounds of ammunition, when fired at short distances also pose danger to the user due to the fragmenting bodies or “fragments.” As used herein, the term “non-fragmenting” grenade refers to a round that minimizes or greatly reduces the hazardous fragments of shrapnel upon explosion.
These standard low-velocity, launcher-fired 40 mm grenades generally have explosive loads of less than 50 grams. Although other manufacturers have attempted to improve these 40 mm grenades, their explosive loads are usually less than 50 grams and they may not be effective on a wide variety of doors. Additionally, some 40 mm grenades with higher explosive loads still have fragmenting bodies that pose danger to the user. During the breaching of a door, fragmentation is a serious danger to the user and to bystanders.
The 40 mm Hellhound by Martin Electronics Incorporated (MEI) is another widely used low-velocity grenade designed to be fired from a 40 mm grenade launcher. The Hellhound has been designed to have a fragmentation radius that is twice that of the standard M-433 grenade. This increases the risk to the gunner and the probability of collateral damage, making the Hellhound not practical for the breaching of doors and barricades and more lethal than ordinary 40 mm grenades.
The HE/DB07 40×46 mm door-breacher, available from American Rheinmetall Munitions, Inc., is another low-velocity grenade designed for breaching doors. The DB07 round differs from conventional high explosive (HE) grenades in that it is designed to enhance blast but reduce fragmentation. However, this round has two significant disadvantages when used for defeating doors and barricades. First, the explosive charge is undersized and has difficulty defeating the wide variety of doors in the target set. Second, the fuze is at the rear of the explosive charge so that when the round detonates the fuze fragments are sent back toward the gunner, greatly increasing his risk of injury.
The previous grenade designs pose a risk of injury to the gunner due to shrapnel and may not generate the overpressure required to defeat a door or barricade.
U.S. Pat. No. 6,408,765 reports a door-breaching device with a safety adaptor for controlled blasting of an object at short range using a gun-launched system. The blasting element in the device includes an explosive charge contained within a housing; the blasting element blasts the object from a preset distance. A stand-off rod with a length equal to the preset distance is connected to the housing. A pyrotechnic lead pellet is reported to detonate the explosive charge upon impact of the stand-off rod with the object. The tail, connected to the blasting element through a safety connector, reportedly reduces shock forces acting on the tail resulting from detonation of the explosive charge and reduces the risk of tail or any other parts being propelled rearwards causing injury to the operator or other bystanders.
U.S. Patent Publication Nos. 2011/0174187 and 2012/0216698 report a door-breaching projectile system using a modified 40 mm grenade round designed to breach doors without throwing a substantial amount of shrapnel into a building's interior. The modified round has a standoff device located on its forward end, which detonates the explosive charge within the projectile before the nose of the projectile strikes the target. This early detonation throws a pressure wave again the door's exterior, forcing the door inward. Shrapnel produced by the detonation remains primarily outside the door. Thus, the projectile is reportedly able to blow open a door without throwing a significant amount of shrapnel into a building's interior.
U.S. Pat. No. 7,000,545 reports a multifunctional breaching apparatus for gaining entry by explosive forces using a hand-placed system. The reference states that the breaching apparatus has a housing made of a flexible polymeric material that disintegrates upon explosion, without significant fragmentation. An explosive element in the housing is reported to be capable of producing sufficient explosive force to breach a structure. The breaching apparatus has a flexible detonating cord or explosive wire wound or wrapped around partitions encased in the housing. A detonator device is placed in line with the detonator cord to initiate the explosive force. The housing is mounted or affixed to any structure (e.g., doors or buildings) by various attachment devices or is attached to a robotic arm, for safe remote operation. The structure is reported to help prolong the time duration of the pushing force of the breaching apparatus while simultaneously producing a controlled explosive force to breach a door (without fragmentizing the door) and free locking bolts from their moorings, without harming the rest of the building or nearby structures or buildings. The breaching apparatus contains hollow chambers holding detonators and positioned close to the housing surface attached to the structure to be breached (e.g., windows or shutters), so that most of the explosive force is directed towards the structure being breached.
U.S. Pat. No. 6,179,944 reports a process for preparing thin-walled, lightweight, non-fragmenting warhead composite casings for use as explosive warheads. The warhead casing is prepared from thermosetting epoxy resin and carbon fibers. The epoxy resin is a liquid, low viscosity resin at ambient temperatures, curable at temperatures ranging up to 175° F. and having a glass transition temperature Tg range from 200° F. to 250° F. The warhead casing is reported to be capable of losing its structural integrity at temperatures below the ignition temperature of the explosive in the casing, thus eliminating or minimizing the likelihood of undesirable explosive reactions caused by high temperatures.
U.S. Pat. No. 5,883,328 reports a tactical smoothbore breaching device for use with shotguns for breaching structures such as doors, windows and gates. The ammunition is loaded into the gun, aimed at the target and is discharged. The force of the projectile is reported to breach a door hinge or door lock and disintegrate while imparting the force to the target so that only a small amount of debris, primarily dust, enters the structure, while destroying the door, lock or gate with minimal blowback toward the shooter.
The known grenades currently produced are not effective against a wide variety of doors and barricades and do not overcome all of disadvantages of fragmentation, leading to personal injury and collateral damage, and insufficient explosive charge and overpressure required to defeat such doors or barricades. Methods for breaching a door using an explosive charge placed on the door, a shotgun round at point-blank range or a battering ram still expose personnel to risk of death or injury.
The new short-range, self-propelled, non-fragmenting door-breaching 40 mm grenade of the invention overcomes these shortcomings and may be used to breach a wide variety of doors and barricades with high efficiency, high gunner safety and low collateral damage. The present invention greatly reduces the risk to the operators allowing them to remain undercover and increases their safety during the door-breaching process.